Well, when will he let us know the results of his own independent inquiry into what happened? He's been awfully quiet...
According to the NFLPA it was trace amounts of Ostarine, which is in most pre-workouts and isn't even scientifically proven to do anything. And the more I read on it today, it appears there is concern about damage it causes to the liver more than any potential enhancement it does to muscle growth. Ostarine is thought to accelerate muscle growth, not enhance recovery.
"People use ostarine for athletic performance, involuntary weight loss due to illness, breast cancer, and many other conditions, but there is no good scientific evidence to support these uses."